(This is the question talking)
Even I don't know the answer,
Until I am posted.
All I know is the length,
5 characters that is.
Random it is,
But less than the 64 base youtube id.
This is what identifies me.
What is he talking about? What is the answer?

Today, I saw this strange message on my facebook's wall.
I can't read what she wrote.
but, I know she is struggling with her feeling.
When I asked her, she said the message is obvious, no need to decrypt it.
What does the message say?
1 \/\/1$!-! 1 /\/3\/312 11137 yo!_! $o 1 \/\/o!_!|_!>/\/...

Yes, I knew that cabriolets are convertibles, but not that they used to be horse-drawn carriages. And I didn't know the jazz enthusiasts, although that seems to be a bit of a crossword staple. But I got the capital of Oregon right away ...

Everything in the next section is flavor text only. You may skip right over it, if you´re impatient.
"So, how did it go officer? I hope there was no blunder this time!"
The chief commander looks rather stern and critical at the small group of men in front of him.
"We´ve spent months to g...

Well, I could solve the last safe, but what did it buy me? Just another instant-teleport and boom... here I am again!
In a single room with very few things around me, most notably a safe, and no door out. Just great. Somehow I can't fight the feeling that I'm tested in a more and more chall...

Suppose I have a binary vector a = (0,1,1,1,0,0) of length $N$. I want to detect in a linear way whether a has any gaps in consecutive 1's. a as defined above has no gaps. But b = (0,1,0,1,0,0) has gaps.
Quadratic solution:
$$\sum_i^N a_i - \sum_i^{N-1}a_i a_{i+1} \le 1$$
Linear solution:
$$?$$...

We are searching for a number.
It is over 400 years old.
Even longer ago there were people who said it wouldn't be so hot on your tongue.
(I thought of this myself. Because English is not my mother language I would really like to see a better phrasing or even the same riddle in poem form.)

sequel of: Which of my friends has a birthday today?
Hello. It's me again. Today is my birthday! So of course I met my friends today, along with a new friend that I made the other day. This new friend of mine is called Felicity. Unfortunately, they're up to it again, and it seems that they have ...

There are three special right triangles, all of their edge lengths are positive integers.
One of the triangles' longer leg, the other triangle's shorter leg and hypotenuse of the last triangle are all equal to each other.
What is the least value of the shortest hypotenuse among these triang...

The question is:
If 7 + 16 = 1000 what is 23 + 42?
Note, that I currently do not have the solution for this riddle, which is not publicly available.
I have already tried the following:
Input base 14 and output base 3, which would yield 10022
Base 987 calculation: 7 + 987*1 + 6 = 1000, 2*987+...